On:
Junit Pioneer
JUnit Pioneer is a JUnit extension that provides extra functionalities that make unit and integration testing a bit easier and simpler.
One extension that I really like are the variety argument sources, that expand JUnit parameterized test cases, abstracting away parsing code for different sources. There is also "retry on fail," which lets you retry a test a number of times.
See the extension's other features here: https://junit-pioneer.org/docs/
Httpie
I am very sure that the CLI app is very popular, but the desktop application is competent.
It is a simple REST client.
It is not feature-rich like Postman, but it is much lighter and doesn't require a login or an account.
Honorable mention is hoppscotch, a REST client that can be used online and can be installed as a PWA.
jmeter-java-dsl
https://abstracta.github.io/jmeter-java-dsl/
JMeter in a domain-specific language.
This tool can not only create JMX projects but also import them.
So if you ever need a small JMX to run as a part of the pipeline or a build, this is it, since you can run it in a Maven build. In addition, this project also offers features for testing at scale and recording test cases.